Efficacy and comparability of thiazide-type diuretics

Efficacy and Comparability of
Thiazide-type Diuretics
Chlorthalidone vs. Hydrochlorthiazide
(HCTZ)/ Triamterene in Hypertensives
Chlorthalidone (50 mg/day) was compared
to HCTZ plus triamterene (25/50 and
50/100 mg/day) in 126 patients with DBP
90-115 mm Hg over an 8-week treatment
period in a 3-arm double-blind, placebo-
controlled randomized trial.
Clark EC, et al. Southern Med J. 1979;72:798-802.
Chlorthalidone vs. Hydrochlorthiazide
(HCTZ)/ Triamterene in Hypertensives
H50/T100
130
120
110
All drugs produced a
significant reduction in BP
from placebo
sig. lower than H25/T50
80 placebo drug placebo drug
Clark EC, et al. Southern Med J. 1979;72:798-802.
Chlorthalidone vs. Hydrochlorthiazide
(HCTZ)/ Triamterene in Hypertensives
• All three regimens significantly reduced
SBP and DBP at every week of therapy
• Significant BP differences between
chlorthalidone and HCTZ/triamterene
(25/50 mg) were found, but not for
chlorthalidone compared to
HCTZ/triamterene (50/100 mg) or
between the two HCTZ formulations
Clark EC, et al. Southern Med J. 1979;72:798-802.
Chlorthalidone vs. Hydrochlorthiazide
(HCTZ)/ Triamterene in Hypertensives
• Once daily administration of
HCTZ/triamterene was effective in patients
with diastolic hypertension, although
HCTZ/triamterene at the lower dose (25/50
mg) was less effective than 50 mg of
chlorthalidone.
Clark EC, et al. Southern Med J. 1979;72:798-802.
Dose-Response to Chlorthalidone in
Patients with Stage 1 Hypertension
4 doses of chlorthalidone (12.5, 25, 50, 75
mg) were compared to placebo for 12
weeks of treatment in 100 patients with
DBP of 90-109 mm Hg.
Success was defined as DBP <90 mm Hg
and/or decrease of 10 mm Hg or more at
the final visit.
Materson BJ, et al. Clin Pharmacol Ther. 1978;24:192-198.
Dose-Response to Chlorthalidone in
Patients with Stage 1 Hypertension
sig. reduction
compared to
systolic- diastolic - systolic - diastolic -
standing
standing
Materson BJ, et al. Clin Pharmacol Ther. 1978;24:192-198.
Dose-Response to Chlorthalidone in
Patients with Stage 1 Hypertension
• Although chlorthalidone 12.5 mg was superior to
placebo in reducing supine and standing systolic
BP, there were no differences in standing systolic
BP for doses between 25 and 75 mg.
• Diastolic success rates were not significantly
different among all active doses: 45% (12.5 mg),
35% (25 mg), 41% (50 mg), and 42% (75 mg)
• The decline in serum potassium was worse than
placebo only with the 50 and 75 mg doses
• No changes in serum uric acid, serum glucose, or
serum sodium were observed.
Materson BJ, et al. Clin Pharmacol Ther. 1978;24:192-198.
Dose-Response to Chlorthalidone in
Patients with Stage 1 Hypertension
• 25 mg of chlorthalidone was as effective
as 50 and 75 mg doses for treatment of
hypertension, with fewer adverse effects.
• 12.5 mg of chlorthalidone was also
effective, although the decline in blood
pressure was smaller than that achieved
by the larger doses.
Materson BJ, et al. Clin Pharmacol Ther. 1978;24:192-198.
Chlorthalidone vs. Hydrochlorthiazide
(HCTZ) in Moderate Hypertensives
Chlorthalidone (50 mg once per day) was
compared to hydrochlorthiazide (50 mg
twice per day)
• 55 patients
• DBP 100-120 mm Hg
• 4 week treatment period
Finnerty FA. Angiology. 1976;27:738-744.
Chlorthalidone 50 mg vs. HCTZ 50 mg BID
in Hypertensives with DBP 100-120 mm Hg
Chlorthalidone 50 mg QD
HCTZ 50 mg BID
160 SBP
140
baseline
Finnerty FA. Angiology. 1976;27:738-744.
Chlorthalidone vs. HCTZ in
Moderate Hypertensives
• Both treatment groups experienced a significant
reduction in SBP and DBP during treatment, with
no significant differences between groups.
• Near normotensive mean DBP levels were
achieved by both groups within two weeks, and
were sustained for the duration of the study.
• Serum potassium declined significantly only in
the HCTZ group.
• No other significant changes were found in serum
sodium, serum creatinine, serum cholesterol, or
fasting glucose.
Finnerty FA. Angiology. 1976;27:738-744.
Chlorthalidone vs. HCTZ in
Moderate Hypertensives
• Chlorthalidone 50 mg QD and HCTZ 50 mg
BID were equally effective in reducing BP.
• Chlorthalidone was associated with fewer
side-effects when given at ½ the HCTZ dose.
Finnerty FA. Angiology. 1976;27:738-744.
Pharmacokinetic and Pharmacodynamic
Comparisons of HCTZ and Chlorthalidone
Conclusions (I)
1. In these studies chlorthalidone 25 mg/d or
HCTZ 50 mg/d lowered BP as well as higher
doses with fewer adverse effects.
2. Lower doses (chlorthalidone 12.5 mg or
HCTZ 25 mg) were effective in lowering BP,
but less so than chlorthalidone 25 mg or
HCTZ 50 mg.
3. Chlorthalidone has a considerably longer
duration of action than HCTZ.
Conclusions (II)
4. The ideal dose-comparison trial of HCTZ
versus chlorthalidone has not yet been
conducted.
5. Low-moderate dose diuretics are
consistent in showing a reduction of
events in morbidity and mortality trials.

Source: https://ccct.sph.uth.tmc.edu/allhat/Slides/Efficacy.pdf